Hey, welcome to the forum 
I’d definitely recommend you check for the usual windows gotcha of “the antivirus is slowing things down to a crawl” if you haven’t already: FAQ — restic 0.18.1 documentation
As you already saw in the FAQ, this should not happen. There’s a more technical explanation as to why not by fd0 here, which you might find interesting: Aborted Backups - #4 by fd0
From your description, it sounds like you’re seeing the files being scanned again, but without seeing the output of the restic command it’s not possible to say for certain.